单选题In a four-stroke cycle diesel engine the intake valves open （）A before TDC and close after BDCB after TDC and close after BDCC before TDC and close before BDCD after TDC and close before BDC

题目
单选题
In a four-stroke cycle diesel engine the intake valves open （）
A

before TDC and close after BDC

B

after TDC and close after BDC

C

before TDC and close before BDC

D

after TDC and close before BDC

相似考题

1.Proper lubrication of the main bearings is more easily obtained in a single acting, four-stroke/cycle diesel engine than in a tow-stroke/cycle diesel engine because________.A.The direction of pressure on the journal in four-stroke engine is continuouslyB.positive feed lubricators are installed on all bearings of four-stroke engine, whereas as a splash feed system is used on tow-stroke engineC.four-stroke engines usually utilize a heavier grade of oil than tow-stroke enginesD.Low-stroke engines usually consume less lube oil than four-stroke engines

2.During the valve overlap period, the exhaust pressure of a turbocharged four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure ______.A.effective cylinder scavenging and coolingB.constant pressure from the turbochargersC.cooler operation of the exhaust systemD.effective constant pressure for turbocharger operation

3.单选题For an ordinary four-stroke diesel engine the exhaust valves close （）.A after TDCB before TDCC after BDCD before BDC

4.Fuel is admitted to a diesel engine cylinder through the ______.A.injector nozzlesB.carburetorC.exhaust portsD.intake valves

更多“In a four-stroke cycle diesel engine the intake valves open”相关问题

  • 第1题：

    单选题
    In a diesel engine, exhaust valves open before the intake ports are uncovered to （） Ⅰ.reduce pumping losses Ⅱ.reduce back pressure
    A

    Ⅰonly

    B

    Ⅱonly

    C

    bothⅠand Ⅱ

    D

    neitherⅠnor Ⅱ


    正确答案： B
    解析： 暂无解析

  • 第2题：

    单选题
    Proper lubrication of the main bearings is more easily obtained in a single acting, four-stroke/cycle diesel engine than in a tow-stroke/cycle diesel engine because（）.
    A

    The direction of pressure on the journal in four-stroke engine is continuously

    B

    positive feed lubricators are installed on all bearings of four-stroke engine, whereas as a splash feed system is used on tow-stroke engine

    C

    four-stroke engines usually utilize a heavier grade of oil than tow-stroke engines

    D

    Low-stroke engines usually consume less lube oil than four-stroke engines


    正确答案： B
    解析： 暂无解析

  • 第3题：

    单选题
    The intake valves in a diesel engine are reseated by （）.
    A

    cam followers

    B

    push rods

    C

    combustion gases

    D

    valve springs


    正确答案： C
    解析： 暂无解析

  • 第4题：

    单选题
    Scavenging in a four-stroke/cycle diesel engine occurs during the （）.
    A

    last part of the exhaust stroke, and the first part of the intake stroke

    B

    last part of the intake stroke only

    C

    early part of the injection stroke only

    D

    early part of the power stroke


    正确答案： A
    解析： 暂无解析

  • 第5题：

    单选题
    Diesel engine valve springs function to （）
    A

    hold the valves open

    B

    keep the valves off their seats until the exhaust stroke is completed

    C

    close the valves

    D

    open inlet valves when the air injection cycle begins


    正确答案： C
    解析： 暂无解析

  • 第6题：

    单选题
    If all other conditions such as bore, stroke, speed, and mean effective pressures are equal, a two-stroke/cycle diesel engine will develop approximately（）
    A

    the same indicated horsepower as a four-stroke/cycle engine

    B

    twice the indicated horsepower as a four-stroke/cycle engine

    C

    one half indicated horsepower as a four-stroke/cycle engine

    D

    one power stroke for every two crankshaft revolutions


    正确答案： D
    解析： 暂无解析

  • 第7题：

    单选题
    The speed of the turbocharger for a four-stroke/cycle diesel engine driving a generator at constant speed depends on the （）
    A

    engine speed

    B

    kilowatt load

    C

    fuel injection pressure

    D

    air intake manifold temperature


    正确答案： B
    解析： 暂无解析

  • 第8题：

    单选题
    Fuel oil begins injection into the cylinder of a four-stroke/cycle diesel engine during the （）.
    A

    intake stroke

    B

    exhaust stroke

    C

    power stroke

    D

    compression stroke


    正确答案： B
    解析： 暂无解析

  • 第9题：

    单选题
    If a four-stroke/cycle diesel engine is started by injecting air into the cylinder, the pistons receiving the charge of starting air must be（）
    A

    on the power stroke

    B

    on the exhaust stroke

    C

    at the end of the power stroke

    D

    at the start of the intake stroke


    正确答案： D
    解析： 暂无解析

  • 第10题：

    单选题
    A four-stroke/cycle, 1000horsepower diesel engine fails to start at normal cranking speed with normal fuel pressure and ambient temperatureThe reason for the failure could be（）
    A

    glazed liners or pistons

    B

    high lube oil pressure

    C

    excessive compression ratio

    D

    worn valve seats and valves


    正确答案： C
    解析： 暂无解析

  • 第11题：

    单选题
    In a turbocharged four-stroke/cycle diesel engine, the exhaust valve remains open until after top dead center and the intake valve opens before top dead center to（）.
    A

    produce a scavenging effect in the combustion space

    B

    equalize cylinder and exhaust manifold pressures

    C

    alleviate the difference in valve size between the intake and exhaust

    D

    flush out condensate that collects after each compression stroke


    正确答案： B
    解析： 暂无解析

  • 第12题：

    单选题
    The intake ports of a two-strike/cycle diesel engine are opened and closed by the action of the （）
    A

    camshaft

    B

    piston movement

    C

    exhaust valves

    D

    vertical drive


    正确答案： C
    解析： 暂无解析

  • 第13题：

    单选题
    The size of the exhaust valve opening is （）
    A

    most critical in a four-stroke cycle diesel engine

    B

    most critical in a two-stroke/cycle diesel engine

    C

    most critical in a four-stroke/cycle diesel engine if it is turbocharged

    D

    of equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cycle diesel engine


    正确答案： A
    解析： 暂无解析

  • 第14题：

    单选题
    During the valve overlap period, the exhaust pressure of a turbochargers, four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure （）
    A

    effective cylinder scavenging and cooling

    B

    constant pressure from the turbochargers

    C

    cooler operation of the exhaust system

    D

    effective constant pressure for turbocharger operation


    正确答案： A
    解析： 暂无解析

  • 第15题：

    单选题
    Proper lubrication of the main bearing is more easily obtained in a single acting four-stroke/cycle diesel engine than in a single acting two-stroke/cycle diesel engine because （）
    A

    bearing pressure in a four-stroke/cycle acting single diesel engine is continually reversed

    B

    bearing pressure in a two-stroke/cycle single acting diesel engine is continually reversed

    C

    the maximum bearing pressure is higher in a single acting two-stroke/cycle diesel engine

    D

    two-stoke/cycle diesel engines require more complicated lubrication piping


    正确答案： B
    解析： 暂无解析

  • 第16题：

    单选题
    For an ordinary four-stroke engine the inlet valves open （）
    A

    after TDC

    B

    before TDC

    C

    after BDC

    D

    before BDC


    正确答案： A
    解析： 暂无解析

  • 第17题：

    单选题
    Which of the following statements is true regarding the installation of piston rings on two-stroke/cycle, diesel engines as compared to four-stroke/cycle, diesel engines?（）
    A

    In a two-stroke/cycle engine, the rings run hotter, requiring the end gap to be greater

    B

    Some provision must be made in a two-stroke/cycle engine to keep the rings from binding in the ports

    C

    No gap is required to exist between the ends of the ring when cold in a two-stroke/cycle engine, but a small gap is required in a four-stoke/cycle engine

    D

    The gaps should be staggered on either side of a piston in a two-stroke/cycle engine, while staggering is not necessary in a four-stroke/cycle engine


    正确答案： A
    解析： 暂无解析

  • 第18题：

    单选题
    A two-stroke/cycle diesel engine requires less starting air than a four-stroke/cycle diesel engine, of equal displacement, because the two-stroke/cycle diesel engine（）
    A

    has little or no internal friction

    B

    has a lower effective compression ratio

    C

    operates with scavenge air under a positive pressure

    D

    operates without energy absorbing intake and exhaust strokes


    正确答案： D
    解析： 暂无解析

  • 第19题：

    单选题
    Which of the following conditions can cause above normal air temperature to develop in the intake manifold of a four-stroke/cycle turbo-charged diesel engine?（）
    A

    Clogged air intake falters

    B

    Piston blow-by

    C

    A defective after-cooler

    D

    Faulty exhaust valves


    正确答案： A
    解析： 暂无解析

  • 第20题：

    单选题
    For a given size engine, the two-stroke/cycle diesel engine will deliver more power than a four-stroke/cycle diesel engine because （）.
    A

    it has a longer power stroke

    B

    more air gets into the cylinder each stroke

    C

    it develops twice as many power strokes at the same speed

    D

    higher combustion pressure is developed


    正确答案： D
    解析： 暂无解析

  • 第21题：

    单选题
    A turbocharged, four-stroke/cycle diesel engine has a larger valve overlap than a naturally aspirated four-stroke/cycle diesel engine, in order to in crease the （）.
    A

    temperature of the exhaust gases

    B

    energy supplied to the turbocharger

    C

    air pressure to the intake manifold

    D

    purge of exhausted gases from the cylinders


    正确答案： C
    解析： 暂无解析

  • 第22题：

    单选题
    The camshaft on a four-stroke/cycle diesel engine provides a means to operate the （）.
    A

    fuel injectors

    B

    exhaust valves

    C

    intake valves

    D

    all of the above


    正确答案： D
    解析： 暂无解析

  • 第23题：

    单选题
    A piston in a four-stroke/cycle diesel engine makes four strokes during each （）.
    A

    crankshaft revolution

    B

    mechanical cycle of operation

    C

    period of two combustion cycles

    D

    cycle of two events


    正确答案： B
    解析： 暂无解析

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